Recent developments in highly advanced electrotechnological equipment, such as superconducting magnets, magnetically levitated vehicles and devices for magnetic resonance imaging, have given rise to previously unexperienced environments in which strong electromagnetic fields are encountered. Potential biohazards of such high magnetic fields have been pointed out, but the influences they may exert on biologic systems are still poorly understood. The purpose of this study is to clarify the biologic actions of extremely low-frequency (ELF) alternate-current (AC) high magnetic fields, especially their effects on gene functions including DNA replication, repair and transcription.As a result, the rate and fidelity of Escherichia coli (E. coli) DNA polymerase-catalyzed DNA synthesis in vitro as well as of E. coli RNA polymerase-catalyzed RNA synthesis did not significantly differ between the reactions exposed and not exposed to 60-Hz of near Tesla orders magnetic fields. The efficiency of mutS-dependent mismatch repair with human cell extracts was also not affected by the magnetic field exposure. The results suggest the core processes of transmission of genetic information may be stable under ELF high magnetic fields. However, the heat shock promoter was activated when Caenorhabditis elegans, carrying an hsp 16 promoter-lacZ reporter chimeric transgene, was exposed up to 0.5T at 60 Hz. This suggests that ELF AC high magnetic fields could elicit certain stress responses in biologic systems.